TurboTorque (TT) Connection

Grant Prideco's industry-leading eXtreme™ Torque (XT™) connections have been meeting the requirements of the most challenging drilling applications for years. These patented connections have proven especially well suited for extended reach, horizontal, deep water, HPHT (High Temperature, High Temperature) and ultra-deep environments. Now, Grant Prideco introduces a new line of connections intended to drill deeper and further, faster than ever before.

TurboTorque™ connections are the industry's first family of connections designed to meet the specific and different needs of each pipe size.

All TurboTorque connections feature a proprietary double-start thread form, making them radically faster than competitive connections.

TurboTorque connections have been thoroughly engineered and tested to validate both design and performance. Tests included finite element analysis, torque-to-yield, multiple make and break, comparative fatigue testing and several field trials.

TurboTorque™ Design Philosophy

For over 25 years, Grant Prideco has taken the lead in the development of rotary-shouldered connections. The double-shouldered HI-TORQUE™ (HT™) connection is still a high-performance workhorse of the drilling industry. Even so, the HT design was based on API thread forms, ultimately limiting performance. The XT design departed from the constraints of API with an improved thread form and reduced taper. This design optimization resulted in additional improvements in torque capacity and streamlined profiles. For completions, under-balanced drilling (UBD) and other pressure sensitive operations, the Grant Prideco™ XT-M™ connection provided the industry’s first pressure rated rotary shouldered connection.

Still leading the industry, Grant Prideco has further refined the development and optimization of rotary shouldered connection design. TurboTorque connections are the industry’s first rotary-shouldered connections that are designed to meet the specific and different needs of each individual pipe size. Taking a “one size does not fit all” approach, the TurboTorque product line is composed of four distinct configurations, optimized to best meet some very specific objectives.

For 3-1/2 to 4-1/2 inch sizes, connection torque capacity is of primary importance. The common use of these sizes makes speed of makeup more desirable than incremental hydraulic gains.

The typical tool joint to pipe body torque and tension ratios for 5 to 5-7/8 inch sizes are relatively balanced. These sizes are commonly used offshore and in higher profile projects. Design must focus on speed of makeup and streamlined connection profiles for increased hydraulic performance.

For the large 6-5/8 inch pipe size commonly run in elevated spread rate projects such as deep water, speed of makeup is a primary design objective. In addition, make-up torques can be excessive, at times surpassing the capacity of the rig equipment. Design parameters must be balanced to reduce the make-up torque and improve hydraulic performance.

TurboTorque™ connections
are the industry’s first rotary-shoudered design to offer a double-start
thread. Dual thread forms, 180 degrees apart, reduce the number of
turns from stab to makeup by 50%. The increase in thread lead angle
provides an increased torque capacity of up to 12%.

Taper is one of the
controlling factors in the final configuration of a rotary-shouldered
connection. TurboTorque’s taper is engineered to ensure a balance
between the pin and box, maximizing fatigue resistance. The taper is
selected to provide for maximum trade-off in torque capacity and speed
of makeup.

TurboTorque’s
proprietary thread form is optimized or each of the four design
configurations. The thread form incorporates a unique dual-root radius –
larger than the root radii of API and even XT™ connections –
significantly reducing peak stress in the thread roots.

The design evolution of TurboTorque connections led to the development of a novel approach for determining the Stress Concentration Factor (SCF) of rotary-shouldered connections (RSC). In most mechanical systems, SCF is defined as a ratio of peak stress to applied normal stress in a similarly strained area. Peak stress is the highest principal stress that normally occurs at a geometric discontinuity, usually a thread root in the case of a rotary-shouldered connection. Current industry methods for determining SCF do not consider the large pre-load stress induced by the make-up torque in a rotary-shouldered connection.

Taking the large pre-load into account, Grant Prideco has developed a new methodology for more accurately predicting the worst case peak stress for a given pipe load. This more accurate method uses Finite Element Analysis (FEA) as the primary tool to explore the maximum peak stress trends in rotary-shouldered connections and to calculate the SCF. The Grant Prideco™ RSC SCF methodology provides an accurate method to compare the relative peak stress trends and SCF values among various rotary-shouldered connection designs to assist in evaluation and selection of connections for drilling, completion and open-water applications.

The SCF values for TurboTorque390, TurboTorque585, API NC38 and 5-1/2 are shown for comparison in the adjacent table for various common tool joint sizes. TurboTorque connections provide a step-change improvement in peak stress reduction and enhanced fatigue performance while offering substantially more streamlined profiles.

TurboTorque™’s performance improvements are best illustrated by a comparison
to both an API connection and to XT™ for specific drill pipe sizes. The
following drill pipe sizes with API connections are typically used:

Offshore -

3-1/2 in. 13.30 lb/ft EU S-135 Range2

5-1/2 in. 24.70 lb/ft IEU S-135 Range2

Onshore -

4-1/2 in. 16.60 lb/ft IEU S-135 Range2

Due to their streamlined profile, TurboTorque and XT connections permit use
of a larger pipe size than do API connections for similar hole sizes.